Add CSI connection

Gopkg.toml

@@ -0,0 +1,54 @@
+
+# Gopkg.toml example
+#
+# Refer to https://github.com/golang/dep/blob/master/docs/Gopkg.toml.md
+# for detailed Gopkg.toml documentation.
+#
+# required = ["github.com/user/thing/cmd/thing"]
+# ignored = ["github.com/user/project/pkgX", "bitbucket.org/user/project/pkgA/pkgY"]
+#
+# [[constraint]]
+#   name = "github.com/user/project"
+#   version = "1.0.0"
+#
+# [[constraint]]
+#   name = "github.com/user/project2"
+#   branch = "dev"
+#   source = "github.com/myfork/project2"
+#
+# [[override]]
+#  name = "github.com/x/y"
+#  version = "2.4.0"
+
+
+[[constraint]]
+  branch = "master"
+  name = "github.com/container-storage-interface/spec"
+
+[[constraint]]
+  branch = "master"
+  name = "github.com/golang/glog"
+
+[[constraint]]
+  name = "github.com/golang/mock"
+  version = "1.0.0"
+
+[[constraint]]
+  branch = "master"
+  name = "github.com/kubernetes-csi/csi-test"
+
+[[constraint]]
+  name = "google.golang.org/grpc"
+  version = "1.7.1"
+
+[[constraint]]
+  branch = "master"
+  name = "k8s.io/api"
+
+[[constraint]]
+  branch = "master"
+  name = "k8s.io/apimachinery"
+
+[[constraint]]
+  name = "k8s.io/client-go"
+  version = "5.0.1"

README.md

@@ -2,15 +2,55 @@
 
 The csi-attacher is part of Kubernetes implementation of [Container Storage Interface (CSI)](https://github.com/container-storage-interface/spec).
 
-## Design
+## Overview
 
 In short, it's an external controller that monitors `VolumeAttachment` objects and attaches/detaches volumes to/from nodes. Full design can be found at Kubernetes proposal at https://github.com/kubernetes/community/pull/1258. TODO: update the link after merge.
 
 There is no plan to implement a generic external attacher library, csi-attacher is the only external attacher that exists. If this proves false in future, splitting a generic external-attacher library should be possible with some effort.
 
+## Design
+
+External attacher follows [controller](https://github.com/kubernetes/community/blob/master/contributors/devel/controllers.md) pattern and uses informers to watch for `VolumeAttachment` and `PersistentVolume` create/update/delete events. It filters out `VolumeAttachment` instances with `Attacher==<CSI driver name>` and processes these events in workqueues with exponential backoff. Real handling is deferred to `Handler` interface.
+
+`Handler` interface has two implementations, trivial and real one.
+
+### Trivial handler
+
+Trivial handler will be used for CSI drivers that don't support `ControllerPublish` calls and marks all `VolumeAttachment` as attached. It does not use any finalizers. This attacher can also be used for testing.
+
+### Real attacher
+
+"Real" attacher talks to CSI over socket (`/run/csi/socket` by default, configurable by `-csi-address`). The attacher tries to connect for `-connection-timeout` (1 minute by default), allowing CSI driver to start and create its server socket a bit later.
+
+The attacher then:
+
+* Discovers the supported attacher name by `GetPluginInfo` calls. The attacher only processes `VolumeAttachment` instances that have `Attacher==GetPluginInfoResponse.Name`.
+* Uses `ControllerGetCapabilities` to find out if CSI driver supports `ControllerPublish` calls. It degrades to trivial mode if not.
+* Processes `VolumeAttach` instances and attaches/detaches volumes. TBD: details + VolumeAttachment finalizers.
+* TBD: PV finalizers.
+* TBD: async operations - we can't block worker queue for 20 minutes (= current AWS attach timeout).
+
 ## Usage
 
-TBD
+### Dummy mode
+
+Dummy attacher watches for `VolumeAttachment` instances with `Attacher=="csi/dummy"` and marks them attached. It does not use any finalizers and is useful for testing.
+
+To run dummy attacher in `hack/local-up-cluster.sh` environment:
+
+```sh
+$ csi-attacher -dummy -kubeconfig=~/kube/config -v 5
+```
+
+TBD: running as a pod
+
+### Real attacher
+
+```sh
+$ csi-attacher -kubeconfig=~/kube/config -v 5 -csi-address /run/csi/socket
+```
+
+TBD: running as a pod
 
 ## Vendoring